Work holder for grinding machines



May 27, 19 30. A. M. DRAKE WORK HOLDER FOR GRINDING MACHINES Filed Aug. 8. 1929 2 Sheets-Sheet 1 J .A'cZen W. Ira/Fe:

y 7, 1930. A. MQDRAKE v 1,760,587

WORK HOLDER FOR GRINDING MACHINES Filed Aug 8, 1939 2 Sheets-Sheet 2 x I 23" A Patented May 27, 1930 UNITEDSTATES PATENT ()FFICE ALDEN M. DRAKE, F GREENFIELD, MASSACHUSETTS, ASSIGNOR TO GREENFIELD TAI 6'0 DIE CORPORATION, OF GREENFIELI), MASSACHUSETTS, A CORPORATION OF MAS- WORK HCLDER FOR GRINDING MACHINES Application filed. August 8, 1929. Serial No. 384,339.

independently centered but in which all of ments and combinations of parts whichwill the pieces are iirmly secured and held durmg the 11130111118 operations thereon. 7

My invention further relates toarrangebe hereinafter described and more particularly pointed out in the appended claims.

rA'preterred form of the invention is shown in the drawings in which a Fig. 1 is an end elevation of parts of a grinding machine embodying my improvements Fig. 2 is a sectional side elevation, taken along the line 22 in Fig. 1;

Fig. 3 is an end view of my improved workholder looking in the direction of the arrow 3 in Fig. l;

Fig. 4 is a side elevation thereof; and

Fig. 5is a detail view,to be described.

Referring to the drawings, I have shown a plate adapted to be secured to the end of a large hollow rotatable work spindle 21 suit-- ablymounted in a grinding machine. The plate 20 is provided with an outwardly projecting hub portion 23 within which a bush ing 24 is closely fitted. The bushing 24 has an external flange 25 at its outer end engaging a shoulder 26 on the inside of the hub 23.

At its inner end, the bushing 24 has an internal flange 27 adapted to be engaged by the innermost piece of work W in a work holder 30 to be described.

This work holder 30 is slidable in the bushing 24 and is provided with a flange 31 near the middle of its length which is cut away or slotted, as indicated at 32 (Fig. 3) at the opposite ends of one diameter to receive dogs 33 mounted on a clamping member 35. The

member 35 is slidable on the outer surface of the hub 23 and is provided with a plurality. of springs 36 acting to force the clamping member 35 yieldingly towardthe supporting plate.

the machine and is providedwith depending arms 41 having yoke members 42 adapted to engagethe clamping member behind an outer flange 44 thereof. The shaft may be manually rocked to push the clamping member outward against the tension of the springs 36.

When insertingthe work holder in the machine, the clamping member is first moved outward, after which the work holder 30 is insertechiwith the notches 32 in alignment with the dogs 33. After the notched flange 31 has passed the dogs 33, the work-holder is turned so that the dogs will engage the flange 31,after which the rock shaft is released and the springs 36 force the work-holder yieldinglyinto the bushing 24. My improved work-holder 30, as shown in the drawings, is designed for centering and holding three pieces of work W, W and W which are shown as being in the form of ball races'for anti-friction bearings. These ball races as they come tothe grinding machine are not very accurate in their external diameters and are also not commonly of exactly circular cross section. V

In order that these slightly rough and irregular articles may be separately and accurately centered in the work-holder, I provide a plurality of work-engaging springs and 61. These springs are of double-end construction, as indlcated in Figs. 2 and 5, and are secured on the insideof the workholder 30 in alternate arrangement. -Reference to Fig. 2 will show that the spring 60 engage the two outer piecesot work W and VV while the springs 61 engage the inner and outer pieces W and W The springs 60 and 61 yield slightly to accommodate slight variations in diameter and inaccuracy of cross section, but all of the springs co-operate to bring each inserted piece of workindependently to an averaged centered position. i

The pieces of work are assembled in the holder 30 beforether holder is placed in the A rock shaft 40 is mounted on the frame of machine and the outermost piece W engages ashoulder 75 on the inside of the holder 30. After the three pieces of work are placed in the holder and are centered by the springs 60 and 61 thereof, the holder is placed in the machine and the innermost pieceof Work W en ages the flange 27 previously described.

he springs 36, acting through the clamping member and dogs 33, place substant'a ressure on the pieces of work W, W and 2 and clamp the same firmly between the shoulders or flanges 27 and 75. The work is thus accurately held during the grinding operation and the operator in the meantime loads additional work-holders so that when the grinding on one lot is completed the drical work comprising a hollow cylindrical I sleeve having an internal flange, a hub memher in which said sleeve is centeredand supported, means en gingsaid sleeve for yieldingly seating sai sleeve in said hub member and thereby clamping a plurality of work pieces between the internal flange of said sleeve and a shoulder fixed with respect to said hub member, and means to center the 7 work pieces in the cylindrical sleeve, said means comprising springs mounted on the inner face of said cylindrical sleeve and yieldingly engaging theouter walls of said work pieces. V

2. In a machine tool, a holder ,for cylindrical work comprising a hollow cylindrical sleeve having an internal flange, a hub 1nemher in which said sleeve is centered and supported, means engaging said sleeve for yieldingly seating said sleeve in said hub member and thereby clamping a plurality of work pieces between the internal flange of said sleeve and a shoulder fixed with respect to said hub member, and means to center the work pieces in the cylindrical sleeve, said means comprising a plurality of axially extended double-ended springs, each spring engaging the outer face of one piece of work with one end of said spring and the outer face of another piece of work with the other end of said spring. 7

3. The combination in a work holder as set forth in claim 2, in which the springs are of differentlengths, the shorter springs of Work and the longer springs engaging and centering spaced work pieces.

4. The combination in a Work holder as set forth in claim 2, in which the springs are of different lengths, the shorter springs engaging' and centering two adjacent pieces of work and the longer springs engaging and centering spaced work pieces, said longer and shorter springs being alternately arranged about the inner cylindrical surface of said sleeve.

5. The combination in a work holder as set forth in claim 2, in which each double ended spring is secured to said sleeve at an intermediate point in the length of said spring, while the ends of said spring are free to move radially for a limited distance.

In testimony whereof I have hereunto affixed my signature.

ALDEN M. DRAKE. 

